Theoretical basis
It can be seen from the structural formula that the hydrogen (Na+) on CMC is easily separated in an aqueous solution (usually in the form of sodium salt). Hence, CMC exists in the form of an anion in an aqueous solution. That is, it shows a negative charge. And when the pH of the amphoteric protein is lower than the isoelectric point, its ability to bind protons -COO- groups is much greater than the ability of -NH3+ groups to give protons and shows a positive charge. 80% of the protein in cow's milk is casein, and the isoelectric point of casein is about 4.6, and the pH of the general acid milk beverage is 3.8 to 4.2. Therefore, under acidic conditions, CMC and milk protein can be complexed by charge attraction to form a relatively stable structure and can form a protective film around the protein. This property of CMC is called the microcapsule embedding and binding properties.
Suggested formula for acid milk beverage
1. Basic formula of blended acid milk beverage (calculated by 1000Kg):
Fresh milk (whole milk powder) 350 (33) Kg
Sugar 50Kg
Compound sweetener (50 times) 0.9Kg
CMC3.5～6Kg
Monoglyceride 0.35Kg
Sodium citrate 0.8Kg
Citric acid 3Kg
Lactic acid (80%) 1.5Kg
Note:
1) Milk powder can be replaced by partially hydrolyzed protein, and control protein ≥1%.
2) The final acidity of the product is controlled at about 50-60°T.
3)The soluble solid content is 7.5%～12%.
2. Formula of lactic acid bacteria beverage (calculated according to 1000Kg):
Fermented milk 350～600Kg
White sugar 60Kg
Compound sweetener (50 times) 1Kg
CMC 3.2～8Kg
Monoglyceride 0.35Kg
Sodium citrate 1Kg
Amount of citric acid
Note:
Use citric acid solution to adjust the acidity of the milk, and the final acidity of the product is controlled at about 60-70°T.
The selection points of CMC
FH9 and FH9 extra-high (FVH9) are generally selected for blended yogurt beverages. FH9 has a thick taste, and the addition amount is 0.35%~0.5%, while FH9 extra-high is more refreshing and has a good effect. The addition amount is 0.33%~0.45%.
Lactic acid bacteria beverages generally choose FL100, FM9, and FH9 extra-high (produced by a special process). FL100 is generally a product with a thick taste and a long shelf life, and the addition amount is 0.6% to 0.8%. FM9 is the most widely used product. It has a thick taste and moderate consistency, and the product can reach a longer shelf life. The addition amount is 0.45% to 0.6%. FH9 extra-high lactic acid bacteria beverage products are thick and not greasy, and the addition amount can be small, and the cost is low. It is suitable for making thick lactic acid bacteria beverages with an additional 0.45% to 0.6%.
The use of CMC
Dissolution of CMC: The concentration is generally 0.5% to 2% in aqueous solution. It is best to dry mix with more than three times white sugar before dissolving. Then slowly add it to 65～85℃ stirring hot water. It is best to use a high-speed mixer to dissolve. After the CMC is dissolved for about 15-20 minutes, pass it through a colloid mill and cool it down to 20-40°C for later use.
The key points of the acid milk beverage process
The quality of raw milk (including reconstituted milk): four types of milk, antibiotic milk, mastitis milk, the first milk, and last milk are not suitable for making acidic milk beverages. The protein components of these four kinds of milk have undergone great changes. Their temperature resistance, acid resistance, and salt resistance are also poor and affect milk taste.
In addition, these four types of milk contain a large number of four enzymes (lipase, protease, phosphatase, catalase). These enzymes have more than 10% residue even at 140℃ ultra-high temperature. These enzymes will be revived during milk storage, causing the milk to smell bitter and flatulence during storage, directly affecting the product's shelf life. Generally, you can use a 75% alcohol equivalent test, boiling test, determination of pH and titer acidity of milk, etc., to select raw milk.
Normal milk 75% alcohol test and boiling test are negative. The pH is between 6.4 and 6.8, and the acidity is ≤18°T. Protein coagulation occurs when the acidity is ≥22°T. When the pH is less than 6.4, it is mostly colostrum or sour milk. When pH>6.8, it is mostly mastitis milk or low acidity milk.
(A) Points to note in the process of blended acidic milk drinks
Preparation of yogurt: Preparation of recovery milk: slowly add milk powder to stirred hot water of 50-60℃ (control the amount of water to be more than ten times the amount of milk powder) and fully dissolve it for 15-20 minutes (preferably with a colloid mill over), then cool it down to 40℃ and set aside.
Prepare the CMC solution according to the use of CMC and add it to the prepared milk solution, mix well, and then use a coarse amount of water (minus the amount of water occupied by the acid solution).
Add the acid solution slowly, continuously, and evenly into the milk. Pay attention to the control of acid addition time between 1.5~2 minutes, if the acid addition time is too long, the protein will stay in the isoelectric point for too long, which will cause protein denaturation and seriously affect the stability; if it is too short, the acid dispersion time will be too short, the local acidity of the milk will be too large, and the protein denaturation will be serious. ～It is better to control between 20~25℃.
For homogenization, the natural temperature of the milk is generally sufficient, and the control pressure is 18-25Mpa.
Sterilization temperature: post-sterilization products generally use 85-90°C for 25-30 minutes, and other products generally use ultra-high temperature sterilization at 137-140°C for 3 to 5 seconds.
(B) Points to note in the process of lactic acid bacteria beverage
Determine the protein content of cow's milk, add milk powder to make its milk protein between 2.9% and 4.5%, raise the temperature to 70~75℃, adjust the homogenizer pressure to 18~20Mpa homogenization, then pasteurize with 90~95℃, 15~30 minutes, cool to 42~43℃ then inoculate the prepared strain at 2%~3%, stir for 10~15 minutes to close the stirring. Maintain a constant temperature of 41～43℃ for fermentation. Stop fermentation when the acidity of the milk reaches 85-100°T and quickly cool down to 15-20°C through the cold plate and pour into the tank.
If the protein content of the milk is low, the whey of the fermented milk is too much, and protein flocculent is easy to appear. Pasteurization at 90-95℃ is good for moderate denaturation of the protein. It improves the quality of the fermented milk if the fermentation temperature is too low or the inoculum is too small. It will cause the fermentation time to be too long and the growth of too many miscellaneous bacteria, which will affect the taste and shelf life of the product. Suppose the temperature is too high or the amount of inoculum is too large. In that case, it will cause fermentation too fast, precipitate more whey, or produce hard lumps of protein, affecting the product's stability. In addition, in selecting strains, one can also choose disposable strains, but one should choose as far as possible after the weak acid strains.
Cooldown the CMC liquid to 15~25℃ and mix it with the milk solution and coarsely fix the volume with water (minus the amount of water occupied by the acid), then add the acid to the milk solution slowly, continuously, and evenly (it is better to add acid by spraying method). Mix well and set aside.
Homogenization generally uses the natural temperature of the milk to control the pressure of 15-20Mpa.
Sterilization temperature: Post-sterilization products are generally sterilized at 85-90℃ for 25-30 minutes, while other products are generally sterilized at 110-121℃ for 4-5 seconds or 95-105℃ for 30 seconds by ultra-high temperature.
Source: Food R&D & Production
